1. Technical Field
The present invention relates to a display device having an input sensing function such as a touch-panel-type liquid crystal device. In addition, the invention further relates to an electronic apparatus that is provided with such a display device.
2. Related Art
In the technical field to which the present invention pertains, a variety of display devices having a so-called touch panel input function has been proposed so far. In the configuration of a touch-panel-type liquid crystal device, which is an example of such a display device having a touch panel input function, an optical sensor (i.e., light sensor, photo sensor) is provided for either each of a plurality of pixel units or each of a plurality of groups of pixel units, where each group thereof is made up of a given number of pixel units. With such a configuration, in addition to its basic function of displaying an image by using light that transmits through the pixel units, a liquid crystal device having a touch panel function of the related art allows a user to input information by means of a pointing means (In the following description, the pointing means may be referred to as a “pointing object” with no intention to limit the technical scope of the invention as long as the context allows). The liquid crystal device having a touch panel function of the related art allows a user to input information through the functioning of photo detectors, which are light-sensitive pickup elements. Specifically, the photo detectors such as optical sensors detect either the touching of a variety of pointing objects such as a finger of a user or other pointing member, though not limited thereto, onto the display surface of the liquid crystal device or the moving of such a pointing object over the display surface of the liquid crystal device. By this means, the user can input information into the liquid crystal device.
Some touch-panel-type liquid crystal devices of the related art adopt a horizontal electric-field scheme for the driving of liquid crystal thereof. Specifically, in the horizontal electric-field driving scheme, a horizontal electric field that is generated between pixel electrodes and a common electrode is used for the driving of liquid crystal, where the pixel electrodes are formed on a certain layer over a TFT array substrate whereas the common electrode is formed on another layer over the TFT array substrate. In such a touch-panel-type liquid crystal device of the related art, thin film transistors (TFT), each of which functions as a pixel-switching element, are formed on the TFT array substrate thereof. Examples of the touch-panel-type liquid crystal devices of the related art are described in, for example, the following patent documents: JP-A-2006-209065, JP-A-2006-003857, and JP-A-6-276352. A further example of the touch-panel-type liquid crystal device of the related art is described in, for example, a non-patent document of “ACTIVE-MATRIX FLAT-PANEL DISPLAYS AND DEVICES 2006 Digest”, page 61, Toshiba Matsushita Display Technology Co., Ltd.
A touch-panel-type liquid crystal device of the related art has a disadvantage in that, since it has a complex lamination/layer structure that is formed on the TFT array substrate thereof, it is not practically possible, or at best difficult, to secure a sufficient amount of light that reaches each of optical sensors thereof. Therefore, as a disadvantage of the touch-panel-type liquid crystal device of the related art, it is not possible to ensure a good sensitivity in the detection of a pointing object that is performed by the optical sensors thereof. In addition to such a disadvantage, if electrodes for optical sensors are formed in a manufacturing process that is not the same as the formation process for other components thereof, for example, without any intention of limitation thereto, in the formation of data lines each through/on which a signal is supplied from a circuitry such as a data-line driving circuit, etc., so as to display images, which is the fundamental function of a liquid crystal device, it is inevitable that the manufacturing process of the liquid crystal device will be complex, thereby resulting in an undesirably high cost of production thereof. Moreover, if electrodes for optical sensors are formed in a discreet manner, that is, separately from other components thereof such as data lines and the like, it is inevitable that the open area of a pixel will be narrow. Such a narrow open region of a pixel inevitably degrades the quality of a display image.